When laying an offshore underwater pipeline there is a limit on how close the pipeline can be terminated to its desired target, such as an oil well. One reason is that oilrig platforms obstruct the travel of a pipe laying barge and prevent it from laying the pipeline all the way up to the oil well. Therefore the pipeline end terminates a distance from the oil well terminal and needs to be joined thereto by installing a spool piece. The term “spool piece” refers to a prefabricated section that includes the pipe, fittings and flanges that are pre-assembled on the surface and then transported to the field for insertion between the pipeline end and the oil well terminal.
Invariably divers are required to install the spool pieces underwater while working either at great depths in saturation diving systems or in shallower depths as air divers. Due to seabed sediment being disturbed by movement of the spool piece during installation, there is often zero visibility at the installation location, which makes the installation process more difficult and dangerous.
Current methods of installing a spool piece include the use of a barge or dynamically positioned crane to lower the spool piece along with lift bags, camel bags and DMA's (Dead Man Anchors) allowing manoeuvring of the spool piece into the correct position. Alternatively, sleepers or mattresses or “A” frames are utilised, which all require an additional separate installation to be erected and removed from the site after completion of the spool piece installation. These methods are time consuming as the rigging of the lift bags/camel bags require inflation and deflation and de-rigging.
A further problem is encountered due to surface swells in the water, which often cause erratic movement of the supporting crane. This leads to tooling equipment getting jammed between the spool piece and pipeline or being damaged before proper seating in the bolt holes. All these problems delay completion of the job and also form a major hazard to the divers that can result in injury or loss of limbs, possibly even being fatal.
It is an object of the invention to suggest a pipe connection guide arrangement, which will assist in overcoming these problems.